Trouble Setting Up code-server HTTPS w/MagicDNS

SUPPORT QUESTIONS
1

Tailscale version: 1.28.0
Your operating system & version: Ubuntu 20.04

Following this guide to set up HTTPS w/code-server: Coding on iPad using VSCode, Caddy, and code-server · Tailscale

I am through to this link at the end of the guide (Usage - code-server v4.5.1 docs) and am hitting the following error on the certbot command:

sudo certbot --non-interactive --redirect --agree-tos --nginx -d <machine-name>.<tailnet-domain-alias> -m <email>
Saving debug log to /var/log/letsencrypt/letsencrypt.log
Plugins selected: Authenticator nginx, Installer nginx
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for <machine-name>.<tailnet-domain-alias>
Waiting for verification...
Challenge failed for domain <machine-name>.<tailnet-domain-alias>
http-01 challenge for <machine-name>.<tailnet-domain-alias>
Cleaning up challenges
Some challenges have failed.

IMPORTANT NOTES:
 - The following errors were reported by the server:

   Domain: <machine-name>.<tailnet-domain-alias>
   Type:   dns
   Detail: DNS problem: NXDOMAIN looking up A for
   <machine-name>.<tailnet-domain-alias> - check that a DNS record
   exists for this domain; DNS problem: NXDOMAIN looking up AAAA for
   <machine-name>.<tailnet-domain-alias> - check that a DNS record

I’m a newbie to DNS/HTTPS/NGINX configuration, so hopefully someone more knowledgeable sees this and can fill in the gaps of those two guides for me.

One other important note… I executed the tailscale cert command on my host machine to .crt and.key files, but nothing in the guide points me to do anything with them (unless I missed something), so they are just sitting in the directory that I executed the command from. I have a feeling that I need to do something with the cert or key? Also, the cert file has three certificates back to back to back, which is weird to me compared to something like a rsa private key file. The cert file format looks like this:

-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
...
-----END CERTIFICATE-----

If anyone can let me know why the file is formatted like that I’d be interested to learn.

2

Do the .crt and .key tailscale files need to be passed to nginx somehow? That seems like a pretty big miss in the documentation if so.